This application claims the priority of Swiss Application No. 1727/98, filed Aug. 21, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a magnetically coupled rotary pump.
A rotary pump of this type is known for example from European Patent application EP 0171515. Here, a pump chamber with a flying pump rotor mounted therein on a stationary axis is separated by a statically sealing can motor housing from the motor chamber. The drive motor is connected with an internal rotor fitted with permanent magnets and mounted close to the wall of the can motor housing on the motor chamber side. The pump rotor in turn is connected with an external rotor provided with permanent magnets, which is located close to the wall of the can motor housing on the pump side. In this way, a zero-contact transmission of the rotary movement of the drive motor to the pump rotor is produced, in which no problems with sealing caused by shaft seals can occur.
Pumps of this kind are used in particular for fluid media that require optimum tightness or avoidance of leaks, and in which no movable or dynamic seals are allowed, for example aggressive or toxic media. In order to drain the pump chambers of such pumps, they are usually provided with pump rotor axes that lie horizontally, with separate additional drain stubs having to be provided in the lower area of the pump chamber. These drain stubs, however, must also have to be resealed, and so-called dead spaces can occur at these points in which a residue of the medium to be delivered can remain--in other words complete emptying cannot be achieved. If such a pump is used with the pump rotor axis located vertically, it can be drained without additional drain stubs, but when operation is resumed there is the problem that the space located between the back of the pump rotor and the can motor housing cannot be vented, since no vent stubs can be located in the can motor housing itself. With a lack of venting, however, there is a danger of the pump rotor bearings running dry, which otherwise are lubricated by the medium to be delivered, thus damaging the bearing. This is the case with conventional pumps with a deep cylindrical can motor housing in which the pump rotor has at least one bearing in the inner area of the can motor housing, which in this vertical operating mode cannot be vented sufficiently when filling.
When such pumps are used for sterile techniques, they must be thoroughly cleaned when reinstalled, drained of residue, and sterilized. The pump described at the outset however meets these additional criteria insufficiently; in particular, the intake area is not free of dead spaces due to the conventional use of multi-section stationary axes and the metal threaded bushings located in the pump rotor with shrunk-on slide bearing bushings, resulting in unsatisfactory cleaning and sterilization of the pump chamber.
The goal of the present invention consists in eliminating these disadvantages and providing a pump that is especially suited for sterile applications.
This goal is achieved according to the invention by a rotary pump with a can motor housing sealing its pump chamber on the drive side from a pumped medium. On one side of the can motor housing, a motor-driven permanent magnet rotor is located and, on the other side, another permanent magnet rotor connected with a pump rotor is located. The can motor housing is connected only at its edge with the pump parts. The pump rotor, on its side facing away from the can motor housing in the hub area facing an intake channel, is rotatably mounted on a fixed axis of a pump bearing support, which is located in the intake channel and is permanently connected with the housing of the rotary pump. A bearing bushing is connected with pump rotor by means of a sleeve made of metal shrunk over the bearing bushing and, in cooperation with a bearing axis located on the pump bearing support, forms the single bearing in the form of a slide bearing of the pump rotor.
Additional preferred embodiments are described herein.
As a result of the design, according to the invention, with the pump rotor bearing on the stationary axis of the pump rotor in the form of a one-piece slide bearing which has no gaps or dead spaces (except for the bearing gap) which the medium to be delivered could penetrate, the compact pump interior can be drained completely, cleaned, and disinfected. In addition, the single bearing, when operation is resumed, is immediately flushed by the medium to be delivered and hence cannot run dry and be damaged. In addition, the remaining design as well as the bearing area, like the pump rotor, promote and support these properties in the same way. Advantageously, a very compact and simple design of the pump is thus achieved, which can be maintained and repaired if necessary in a simple fashion.
A pump according to the invention designed in this way is suitable for uses in fluid applications and especially in the field of sterile applications.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.